Heat transfer printing

ABSTRACT

An ink composition for heat transfer printing comprising at least one of carbinol bases of basic dyes or their derivatives, a strong base, a binder and a solvent for dissolving the binder. This ink composition is excellent in storage stability because it contains a carbinol base of a basic dye or its derivative in isolated form as a coloring agent along with a strong base. By using this ink composition, a transfer sheet having high storage stability can be obtained.

This is a division of application Ser. No. 962,901, filed Nov. 22, 1978,now U.S. Pat. No. 4,272,292.

BACKGROUND OF THE INVENTION

This invention relates to an ink composition having high storagestability for use in heat transfer printing of fiber products includingtextiles and fabrics, particularly those of acid-modified syntheticfibers.

Heretofore, a process for heat transfer printing acid-modified syntheticfiber products, such as acrylic fiber and polyester fiber productsdyeable with cationic dyes, with basic dyes (cationic dyes) has beenwidely known as the heat transfer or sublimation transfer process.

Since this process resorts largely to the heat transferability of dyes(which is due mainly to sublimation, but may also be caused by meltingand evaporation in some cases), various processes for increasing theheat transferability of the basic dyes have been proposed. One of suchprocesses is a process wherein a basic dye is used with a base therebyto increase the sublimability of the dye (for instance, Japanese PatentLaid-Open Nos. 12916/1974 and 12917/1974), and another example ofproposed processes is a process wherein a basic dye is converted to acarbinol base thereof or its derivative and then is used as a dye fortransfer printing (for instance, Japanese Patent Laid-Open Nos.18784/1975 and 14889/1975).

Dyes with increased heat transferability obtained in the above describedmanner are advantageous from the viewpoint of heat transfer printingprocedures, but are very disadvantageous when ink compositionscontaining such dyes and transfer sheets obtained by using the same arestored because their storage stability is reduced by the increased heattransferability of the dyes.

For example, in the case of such an ink composition, the dye containedtherein will deteriorate or decompose during storage, and a transfersheet or a transferred pattern obtained by using an ink compositionstored for 1 or 2 months after preparation will be reduced inconcentration and changed in hue in comparison with that obtained byusing the same ink composition freshly prepared. These tendencies areparticularly notable in some dyes.

The aforementioned defects in the conventional ink compositions for heattransfer printing have been considered to be due to the instability ofcarbinol bases or their derivatives which are easily transferable dyes(see, for example, Japanese Patent Laid-Open No. 86691/1974 and "DyeingIndustry", 24(4), pp. 33-46).

Since transfer printers are not ordinarily the same as transfer sheet ortransfer printing ink makers, reduction in storage stability decreasesthe commercial value of transfer sheets or inks for transfer printing toa great extent.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an ink compositionfor heat transfer printing which retains the heat transferability of thedye and also possesses high storage stability.

It is another object of the present invention to provide a transfersheet retaining both the heat transferability of the dye and storagestability, and a heat transfer printing process using the same.

As a result of researches, we have found that these objects can beachieved by causing carbinol bases of basic dyes or their derivatives tocoexist with strong bases in an ink or a coloring layer of a transfersheet.

The ink composition for heat transfer printing according to the presentinvention comprises at least one of carbinol bases of basic dyes ortheir derivatives, a strong base, a binder and a solvent for dissolvingthe binder.

The transfer sheet according to the present invention comprises asubstrate sheet and, provided thereon, a coloring layer of a desiredpattern containing a coloring agent comprising at least one of carbinolbases of basic dyes or their derivatives, a strong base and a binder.

Further, the heat transfer printing process in accordance with thisinvention comprises superposing the above described transfer sheet on atransfer receiving base material (fiber product to be transfer printed)consisting of a fiber dyeable with cationic dyes so that the surfaceprovided with the coloring layer of the former contacts the surface ofthe latter, and maintaining the superposed sheet and material under heatand pressure.

In the light of the teaching of Japanese Patent Laid-Open No. 12916/1974and other references cited earlier that a base is an additive whichserves to convert a stable basic dye to an unstable and heattransferable carbinol base thereof, our finding mentioned hereinabovemay appear unexpected.

Although it is not sufficiently clear why a carbinol base is renderedstable when a strong base is added thereto, one reason for this may bethat the carbinol base per se is not unstable but rather an intermediatebetween the carbinol base and a basic dye is unstable.

Namely, the following equilibrium is known to exist between a salt of abasic dye and a carbinol base thereof: ##STR1## wherein Dy is a cationicmoiety of a basic dye.

If a carbinol base alone is present in an ink composition, anintermediate as shown above may be formed by the action of trace amountsof acids in the air such as CO₂, and the intermediate thus formed, beingunstable, may result in deterioration of a dye component in the inkcomposition.

Further, in the case where NaOH, for example, is used as a base in thebasic dye-base system as disclosed in Japanese Patent Laid-Open No.12916/1974, a salt NaX which is formed through the followingequilibrium: ##STR2## wherein X⁻ is an acid radical, and remains in thesystem is considered to shift the equilibrium leftwards, thuscontributing particularly to formation of an unstable intermediate.

It will be understood from the above hypothesis that prevention of ashift of the equilibrium, i.e., formation of an intermediate, byremoving the unnecessary and deleterious acid residue from the systemand further adding a strong base ensures stability of the inkcomposition.

Since the heat transferability of a dye is due to its nonionic naturerather than to its ionic nature, it will be understood that preventionof formation of an unstable intermediate thereby to retain a stablecarbinol base does not adversely affect the heat transferability of thedye per se.

As set forth hereinabove, the present invention is based on thediscovery that the sublimability of a dye does not always correlate withthe stability thereof.

The nature, utility, and further features of this invention will beapparent from the following detailed description beginning with aconsideration of the general aspects of the invention and concludingwith specific examples of practice illustrating preferred embodiments ofthe invention.

Throughout the accompanying drawings like parts are designated by likereference numerals.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawing,

FIGS. 1 and 2 are sectional views respectively of examples of thetransfer sheet according to the present invention, and

FIG. 3 is a sectional view conceptually showing the printing step in theheat transfer printing process according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in greater detail.

For the carbinol bases of basic dyes or their derivatives according tothis invention, any of those having sublimability at a transfertemperature of from 80° to 250° C. can be used.

For example, the carbinol bases of the basic dyes listed below and theirderivatives are suitable.

Methine basic dyes such as Aizen Cathilon Yellow 3GLH (C.I. Basic Yellow11 manufactured by Hodogaya Kagaku K.K.), Aizen Cathilon Yellow GLH(C.I. Basic Yellow 14, Hodogaya Kagaku K.K.), Astrazon Yellow GRL (C.I.Basic Yellow 29, Beyer A.G.), Diacryl Yellow 3GN (C.I. Basic Yellow 51,Mitsubishi Kasei K.K.), Diacryl Brilliant Yellow 2G-N (C.I. Basic Yellow33, Mitsubishi Kasei K.K.), Diacryl Golden Yellow GL-N (C.I. BasicYellow 28, Mitsubishi Kasei K.K.), Aizen Cathilon Yellow GPLH (C.I.Basic Yellow 48, Hodogaya Kagaku K.K.), Astrazon Orange G (C.I. BasicOrange 21, Beyer A.G.), Aizen Astra Phloxine FF (C.I. Basic Red 12,Hodogaya Kagaku K.K.), Aizen Cathilon Pink FGH (C.I. Basic Red 13,Hodogaya Kagaku K.K.), Sumiacryl Red 10B (C.I. Basic Red 15, SumitomoKagaku Kogyo K.K.), Diacryal Pink R-N (C.I. Basic Red 35, MitsubishiKasei K.K.), Basacryl Brilliant Red G (C.I. Basic Red 52, BadischeA.G.), Diacryl Brilliant Red 3G-N (C.I. Basic Red 68, Mitsubishi KaseiK.K.), Aizen Cathilon Red 6BH (C.I. Basic Violet 7, Hodogaya KagakuK.K.), Sumiacryl Red 5B (C.I. Basic Violet 16, Sumitomo Kagaku KogyoK.K.), Diacryl Brilliant Red 5B-F (C.I. Basic Violet 16, MitsubishiKasei K.K.), Aizen Cathilon Red 7BNH (C.I. Basic Violet 27, HodogayaKagaku K.K.), Aizen Cathilon Brilliant Red SBH (C.I. Basic Violet 40,Hodogaya Kagaku K.K.), and Astrazon Blue FRR (C.I. Basic Blue 69, BeyerA.G.);

Triarylmethane basic dyes such as Aizen Methyl Violet Pure (C.I. BasicViolet 1, Hodogaya Kagaku K.K.), Aizen Crystal Violet (C.I. Basic Violet3, Hodogaya Kagaku K.K.), Aizen Brilliant Basic Cyanine 6GH (C.I. BasicBlue 1, Hodogaya Kagaku K.K.), Astrazon Blue B (C.I. Basic Blue 5, BeyerA.G.), Aizen Diamond Green (C.I. Basic Green 1, Hodogaya Kagaku K.K.),Aizen Malachite Green (C.I. Basic Green 4, Hodogaya Kagaku K.K.),Magenta (C.I. Basic Violet 14), and Victoria Blue (C.I. Basic Violet10);

Monoazo basic dyes such as Astrazon Orange RRL (C.I. Basic Orange 28,Beyer A.G.), Astrazon Red BBL (C.I. Basic Red 23, Beyer A.G.), KayacrylRed GL (C.I. Basic Red 29, Nihon Kayaku K.K.), Astrazon Bordeaux BL(C.I. Basic Violet 19, Beyer A.G.), Kayacryl Blue GRL (C.I. Basic Blue41, Nihon Kayaku K.K.), and Diacryl Blue RBL-N (C.I. Basic Blue 57,Mitsubishi Kasei K.K.);

Cyanine basic dyes such as Aizen Cathilon Brilliant Red 4GH (C.I. BasicRed 14, Hodogaya Kagaku K.K.), Aizen Cathilon Brilliant Yellow 5GLH(C.I. Basic Yellow 13, Hodogaya Kagaku K.K. ), and Diacryl Yellow 2GLN(C.I. Basic Yellow 66, Mitsubishi Kasei K.K.);

Naphthostyryl basic dyes such as Diacryl Brilliant Blue H₂ R-N (C.I.Basic Blue 105(S), Mitsubishi Kasei K.K.), and Diacryl Brilliant BlueHB-N (C.I. Basic Blue 106(S), Mitsubishi Kasei K.K.);

Thiazine basic dyes such as Aizen Methylene Blue FZ (C.I. Basic Blue 9,Hodogaya Kagaku K.K.);

Acridine basic dyes such as Acradine Yellow G (C.I. 46025), Rheonin AL(C.I. 46075), Benzoflavine (C.I. 46065), and Phosphine (C.I. 46045);

Oxazine basic dyes such as Aizen Cathilon Pure Blue 5GH (C.I. Basic Blue3, Hodogaya Kagaku K.K.); and

Xanthene basic dyes such as Aizen Rhodamine BH (C.I. Basic Violet 10,Hodogaya Kagaku K.K.).

The carbinol bases used in the present invention are obtained, forexample, by causing the above enumerated basic dyes to react withalkalis in an aqueous system.

The carbinol base derivatives are those of the ether type obtained, forexample, by causing the same dyes to react with alcoholates in place ofalkalis in a solvent, and represented by the general formula:

    Dy--O--R

wherein Dy is a cationic dye residue, and R is an alkyl group havingfrom 1 to 4 carbon atoms, a benzyl group or a phenyl group.

Of these carbinol base derivatives, those wherein R is a lower alkyl,particularly a methyl or ethyl group are desirable.

These carbinol bases of basic dyes or their derivatives (hereinaftercovered by the term "coloring agent") are ordinarily used in the inkcomposition of this invention in a quantity of from 0.1 to 10%, all thepercentages used herein and hereafter being "% by weight". With lessthan 0.1% of the coloring agent, no sufficient tinting strength will beobtained.

For the strong base used in this invention in combination with thecoloring agent, any of the bases generally known as strong bases can beused.

Examples of these bases are: hydroxides or alcoholates of alkali metalsor alkaline earth metals such as lithium, sodium, potassium, beryllium,magnesium, calcium, barium, and strontium; carbonates or bicarbonates ofthe alkali metals or alkaline earth metals; salts of strong bases andweak acids such as acetates, formates, butyrates, stearates, sulfinates,cyanates, isocyanates, and thiocyanates of alkali metals; phosphates ofalkali metals, and salts of acids capable of causing decarboxylationsuch as sodium tartrate, and sodium oxalate; oxides of alkaline earthmetals or hydrates thereof.

Of the above mentioned strong bases, hydroxides or alcoholates of alkalimetals or alkaline earth metals are particularly desirable. These basescan be used singly or in a combination of two or more members.

The strong base is used in a quantity of from 1 to 40 moles, preferablyfrom 2 to 20 moles, for 1 mole of the coloring agent, and ordinarilyfrom 0.1 to 10%, preferably from 0.5 to 5%, of the ink composition. Lessthan 0.1% of the strong base will not stabilize the coloring agentsatisfactorily, while the addition of more than 10% of the strong basenot only will be useless but also will be undesirable because the otheringredients will be diluted therewith.

As a result of our investigation, it has been found that, in addition tothe state of the coloring agent alone, the state of the ink ingredientsincluding the coloring agent, the strong base, the binder and thesolvent seriously affects the storage stability of the ink or thetransfer sheet. If the respective ingredients are in completelydissolved state, the storage stability of the ink is further improved.In the case of a transfer sheet prepared with an ink containingundissolved ingredients, it is difficult to form on the substrate sheetthereof a coloring layer of a uniformly and densely colored pattern, andsuch a transfer sheet tends to be easily attacked by the ambient air andthus the storage stability thereof would be reduced.

Accordingly, it is preferable that the type and quantity of the strongbase to be used be determined in relation to the solvent, the binder andthe coloring agent, particularly to the solvent, so that an ink incompletely dissolved state can be obtained. When sodium hydroxide andpotassium hydroxide among the above enumerated strong bases are used inthe specified quantity range, particularly high storage stability andgood color development can be achieved.

For the binder, any of film forming organic resins can be used.

Specific examples of such resins are: cellulose derivatives such asethyl cellulose, carboxymethyl cellulose, cellulose butyrate, celluloseacetate, ethylhydroxyethyl cellulose, hydroxypropyl cellulose,hydroxypropyl methyl cellulose, benzyl cellulose, hydroxyethylcellulose, and derivatives of the aforesaid cellulose derivatives;polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinylformal, polycarbonate resins, polyester resins, polyamide resins,silicon resins, furan resins, and aminoplasts; homopolymers orcopolymers of various vinyl monomers, for example, unsaturatedcarboxylic acids such as acrylic acid (including a salt thereof),methacrylic acid, itaconic acid, fumaric acid and maleic acid, or esterderivatives, nitrile derivatives or acid amide derivatives thereof,vinyl chloride, vinylidene chloride, vinyl acetate, styrene, vinylpyrrolidone, vinyl methyl ether, butadiene, ethylene, propylene,isobutene, cumarone, indene, terpene, vinyl acetal, vinyl ether, andvinyl benzal; and halogen containing resins, nitrogen containing vinylpolymers, diene polymers, polyurethane, polyurea, polyether, varioushard resins (such as phenolic resins, modified phenolic resins, modifiedmaleic resins, modified alkyd resins, petroleum resins, ketone resins,xylene resins, ester gum, lime resins, maleic acid-modified rosin, androsin).

These binders should not cause a chemical reaction with the coloringagent or the strong base, and should have an appropriate melt viscositythat would not prevent the sublimation and diffusion of the particles ofthe coloring agent during heat transfer operation.

It is also preferable that the binder be completely dissolved in the inkcomposition, retain good printability and coating properties, and do notaccelerate decomposition of the coloring agent with the lapse of time.

Particularly desirable binders from this standpoint are cellulose ethersor esters such as ethyl cellulose, ethylhydroxyethyl cellulose,hydroxypropyl cellulose, hydroxypropylmethyl cellulose; and vinylpolymers such as polyvinyl alcohol, polyvinyl formal, polyvinyl butyral,polyvinyl acetate and polyvinyl pyrrolidone.

The binder is ordinarily used in the ink composition at a concentrationof from 5 to 20%. When less than 5% of the binder is used, the bindingstrength will be too low, while the use of more than 20% of the bindernot only will be uneconomical but also will be undesirable because theheat transferability and diffusibility of the coloring agent will behindered. As mentioned earlier, it is preferable that the binder have aviscosity suitable for printing or coating at the concentrationspecified herein.

For the solvent which is a major ingredient of the ink composition, atleast a solvent capable of dissolving the binder is used. Examples ofsuch solvents are heptane, isoheptane, isooctane, industrial gasolines#1 (benzine), #2 (rubber gasoline), #3 (soybean gasoline), #4 (mineralspirit) and #5 (cleaning solvent) according to Japanese IndustrialStandards K2201, petroleum benzine, ligroin, cyclohexane,methylcyclohexane, benzene, toluene, xylene, light solvent naphtha,turpentine oil, trichloroethylene, perchloroethylene, dichloropropane,amyl chloride, dichloropentane, monochlorobenzene, O-dichlorobenzene,n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol,sec-butyl alcohol, tert-butyl alcohol, isoamyl alcohol, fusel oil,methyl isobutylcarbinol, 2-ethylbutanol, 2-ethylhexanol, cyclohexanol,phenol, cresol, furfuryl alcohol, tetrahydrofurfuryl alcohol, n-butylether, dichloroethyl ether, anisole, dioxane, butyl formate, amylformate, isopropyl acetate, butyl acetate, sec-butylacetic acid, amylacetate, isoamyl acetate, 2-ethylhexyl acetate, cyclohexylacetic acid,ethyl propionate, butyl propionate, amyl propionate, butyl butyrate,diethyl carbonate, diethyl oxalate, methyl lactate, ethyl lactate,triethyl phosphate, ethylene glycol, ethylene monomethyl ether, ethylenemonobutyl ether, ethylene monoacetate, ethylene monomethyl etheracetate, ethylene monoethyl ether acetate, diethylene glycol, diethylenemonomethyl ether, diethylene monoethyl ether, propylene glycol, hexyleneglycol, furfural, acetal, methyl isobutyl ketone, diisobutyl ketone,mesityl oxide, acetylacetone, diacetone alcohol, cyclohexanone, methylcyclohexanone, nitromethane, nitroethane, 1-nitropropane,2-nitropropane, acetonitrile, diethylamine, triethylamine,cyclohexylamine, aniline, pyridine, picoline, monoethanolamine,morpholine, dimethylformamide, thiophene, sulfolane, dimethyl sulfoxide,lacquer thinner, thinner for vinyl chloride resin coating materials,thinner for cashew resin coating materials, thinner for leadless coatingmaterials for toys, and acetylcellulose thinner. The solvent to be usedin the invention is selected from the above listed solvents so that itdissolves the binder and causes no undesirable interaction with thecoloring agent and the strong base.

The solvent must dissolve the binder as set forth hereinbefore, and ithas further been found desirable that the solvent also dissolve thecoloring agent and the strong base to give an ink composition inuniformly dissolved state.

In order to ensure uniform dissolution of the ingredients including thecoloring agent and the strong base, it is necessary to select a specificsolvent. It has also been found that, even if a solvent system capableof providing uniform dissolution is used, an ink composition possessingsufficient storage stability cannot be obtained unless the components ofthe solvent system and the ratio therebetween, which are of greatimportance, are appropriately selected (see the "solvent test" whichwill be described hereinafter).

In view of the foregoing findings, a solvent system most suitable foruse in this invention is a solvent system comprising 80% by weight ormore of a monohydric alcohol having from 3 to 6, preferably from 4 to 6,carbon atoms singly, or a mixture of said monohydric alcohol and atleast one secondary solvent component selected from butyl acetate,isopropyl acetate, toluene, xylene and methyl isobutyl ketone.

The term "monohydric alcohol" as used herein includes an alcohol whereinpart of the hydrogen in the hydrocarbon moiety is substituted by asubstituent, preferably an alkoxy group, the total carbon atoms beingfrom 3 to 6. An alcohol having less than 3 carbon atoms ensures uniformdissolution, but reduces the storage stability of the ink composition.When an alcohol having more than 6 carbon atoms is used, theprintability, particularly drying efficiency of the ink compositionbecomes poor.

Examples of desirable monohydric alcohols are isopropyl alcohol,butanol, amyl alcohol, methyl amyl alcohol, methyl cellosolve, and ethylcellosolve, among which butanol, amyl alcohol, methyl amyl alcohol, andethyl cellosolve are especially preferable.

These monohydric alcohols are preferably used with at least onesecondary solvent component selected from butyl acetate, isopropylacetate, toluene, xylene, and methyl isobutyl ketone. These secondarysolvent components are used in order to obtain improved viscositystability and printability without reducing the storage stability of theink composition.

The solvent of this invention preferably comprises 80% by weight or moreof at least one of the above enumerated monohydric alcohols singly or atotal of the monohydric alcohol and a secondary solvent component, ifused. This is because a solvent system containing a large quantity ofcomponents other than those specified above reduces the storagestability of the ink composition. For example, the addition of water,methyl alcohol, ethyl alcohol, ethyl acetate and methyl ethyl ketone isundesirable because the storage stability of the ink composition will beadversely affected thereby. For this reason, it is most preferable thatno such solvents and other conventional solvent components be used, andit is preferable that these solvents be used, if desired, in a quantitynot exceeding 20% by weight of the solvent system of this invention.

The ratio of the monohydric alcohol to the secondary solvent componentused ranges from 1/9 to 10/0, preferably from 2/8 to 4/6.

The above described solvent system constitutes the remainder of the inkcomposition of this invention.

The ink composition of this invention may optionally comprise otheradditives commonly used in inks for heat transfer printing thereby toimprove its printability and other properties. For example, as acoloring additive which, when the coloring agent is transfer-printedonto a transfer receiving base material, permeates through the basematerial and causes the micelles to swell, thus effectively enhancingthe permeability of the dye, urea, naphthalene, ammonium tartrate,glycosine A, oxalates of aliphatic amines such as cyclohexylamine,ammonium acetate, benzylamine, and various types of surfactants such asanionic, nonionic and ampholytic surfactants can be used.

Examples of other optional additives are plasticizers, stabilizers,waxes, greases, drying agents, auxiliary drying agents, hardeningagents, emulsifiers, dispersants, thickeners, fillers, pigments anddyes. Among these additives, pigments and dyes are particularly requiredfor the purpose of giving color to the ink, for example, in the casewhere the coloring agent used in this invention develops its color onlywhen it has been transfer-printed, and non-sublimable pigments and dyesare ordinarily used.

These optional additives are used in appropriate quantities in the knownrange according to purposes, and need not necessarily be dissolved inthe ink.

The ink composition of this invention can be obtained by mixing theingredients with the solvent mentioned above by an ordinary method, ifdesired, under heat.

As shown in the sectional view of FIG. 1, the transfer sheet 4 of thisinvention has a substrate sheet 1 consisting of any sheet-form materialsuch as paper and a plastic film onto which the ink composition of theinvention obtained in the above described manner is applied by anyprinting method such as the gravure printing process, offset printingprocess, relief printing process and silk screen process in a quantity,for example, of from 0.2 to 4 g/m² (dry basis) to form a coloring layer2 of any desired pattern on the substrate sheet 1. It is possible, ifdesired, to further provide an overcoat layer 3 consisting of afilm-forming resin over the coloring layer 2 as shown in FIG. 2.

One example of the ratio between the respective components of thecoloring layer 2 is: a coloring agent, 1 to 80%; a strong base, 1 to 40moles, preferably 2 to 20 moles, for 1 mole of the coloring agent, and 1to 80%, preferably 2 to 40%, of the coloring layer; and the remainder, abinder and any optional additives. When less than 1% of the coloringagent is used, only poor color will be developed, while the addition ofmore than 80% of the coloring agent not only will be ineffective butalso will deteriorate the physical properties of the coloring layer. Thestrong base in a quantity less than the lower limit will result in apoor stabilizing effect, while that in a quantity exceeding the upperlimit will be ineffective and undesirable because the other ingredientswill be diluted therewith.

The overcoat layer 3 as shown in FIG. 2 is obtained by applying any ofthe film forming resins, which were set forth hereinbefore as thebinder, dissolved in the above mentioned solvent at a concentration of,for example, from 5 to 20% by means of any coating method such as thebar coating method, the roller coating method and the gravure coatingmethod, and drying the resin to form a layer of from 0.5- to 10-μmthickness.

This overcoat layer 3 may be omitted, and may be provided depending onthe necessity in order to control the contact between the coloring layer2 and the transfer receiving base material.

Next, the heat transfer printing process using a transfer sheet thusobtained according to this invention will be described.

For the base material to receive the transfer pattern in accordance withthis invention, sheet-form materials consisting of fibers dyeable withcationic dyes can be used. Typical examples of such fibers are:polyacrylonitrile, copolymers of acrylonitrile, styrene-p-sulfonate andvinyl compounds such as vinyl chloride, vinylidene chloride, vinylalcohol, methacrylates or amides; or acid-modified polyesters such aspolyesters, particularly aromatic polyesters, modified with acidradicals such as a sulfonic acid group, and polyamides, and blended yarnfiber products or mix-woven fiber products predominantly comprising thesame.

As shown in FIG. 3, a transfer receiving base material 5 consisting ofthe above described fiber dyeable with cationic dyes and the transfersheet 4 are mutually superposed so that the surface provided with thecoloring layer 2 of the latter contacts the surface of the former, andthe superposed base material and sheet are then maintained at atemperature of from 80° to 250° C., preferably from 150° to 230° C., andunder a pressure of from 20 g to 20 kg/cm² for 10 to 180 sec.,preferably 20 to 90 sec., whereby the heat transfer printing process ofthis invention is accomplished.

Heat and pressure can be applied either by interposing the transfersheet 4 and the transfer receiving base material 5 between a pair of hotplates, or by pressing the same against a heating drum. Heating ispreferably applied from the side of the transfer sheet 4.

When the fiber products dyeable with cationic dyes are subjected to theheat transfer printing as described hereinabove, no sufficient colordevelopment may be obtained in some cases. In order to eliminate suchdrawbacks, a preferred embodiment of the present invention involves apretreatment comprising immersing under heat the fibers in a solutioncontaining at least one of compounds having in the molecule thereof anammonium group, an amino group or an acid amide group, organic acids, orinorganic acids (hereinafter referred to as "color developer"); at leastone of nonionic surfactants, or blended nonionic-anionic surfactants(hereinafter referred to as "homogenizing agent"); and water. Bysubjecting the fiber products to this pretreatment, the color developsvery clearly and uniformly, and transfer-printed products with splendidluster and high durability can be obtained in an easy and stable manner.

The pretreating solution basically consists of a color developer, ahomogenizing agent and water, and a solution containing 5 to 100 g of acolor developer and 0.5 to 3 g of a homogenizing agent, respectively,for 1 l of water is preferably used. Less than 5 g of a color developerfor 1 l of water results in a poor color developing effect, while morethan 100 g of this developer causes saturation of a color developingeffect, thus reduces color developing efficiency, and may furtherdeteriorate the fiber product to be transfer-printed depending on thetype of a color developer selected. On the other hand, less than 0.5 gof a homogenizing agent results in a poor soil-removing effect and maysometimes cause uneven dyeing, while more than 3 g of this agent exceedsthe concentration required.

The color developer has in the molecule thereof a dissociable ammoniumcation and a proton, while there is ordinarily a sodium cation at theterminal position of a compound constituting the fiber dyeable withcationic dyes. Accordingly, by subjecting the material to betransfer-printed to a heat treatment in the color developing solution,the ammonium cation and the proton undergo ion exchange with the sodiumcation.

The terminal group of the fiber dyeable with cationic dyes is convertedto --SO₃ NH₄ by the ion exchange, and the terminal portions of the fiberbecome highly active because of the decomposition of ammonium due toheat generated during transfer printing operation, whereby thetransfer-printability of the fiber is enhanced.

For the above mentioned color developer, aqueous ammonia; compoundshaving an ammonium group such as ammonium chloride, ammonium acetate,ammonium nitrate, ammonium sulfate, ammonium phosphate, ammoniumoxalate, ammonium tartrate, and ammonium sulfamate; compounds having anamino group such as methylamine, ethylamine, and sulfamic acid; andcompounds having an acid amide group such as formamide, acetic amide,oxalic amide, and urea; or inorganic acids such as hydrochloric acid,nitric acid, phosphoric acid, and sulfuric acid; and organic acids suchas formic acid, acetic acid, propionic acid, oxalic acid, tartaric acid,and succinic acid, can be used, and any of these compounds or acidsshows remarkable advantages.

For the homogenizing agent, nonionic surfactants such as polyoxyethylenealkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkylesters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkylesters; or blended nonionic-anionic surfactants comprising theaforementioned nonionic surfactants and anionic surfactants such assalts of fatty acid, sulfates of higher alcohols, sulfates of liquidfatty oil, sulfates of aliphatic amines and amides, phosphates of fattyalcohols, sulfates of fatty acid amides, and alkylaryl sulfates can beused.

This homogenizing agent is used in order to remove soil from thematerial to be transfer-printed by utilizing the properties of thesurfactant such as detergency and permeability and also to preventfloating of the material in the treating bath.

In accordance with this invention, a nonionic surfactant or a blendednonionic-anionic surfactant is used as a homogenizing agent since fibersprincipally comprising ionic fibers such as acrylic fibers as describedabove are treated.

To the pretreating solution having the above specified composition,preferably 0.5 to 3 g of an alkali agent per liter of water can furtherbe added depending on the necessity. This alkali agent is particularlypreferably added in order to remove by saponification impurities fromthe material to be transfer-printed which is heavily soiled, forexample, with water-insoluble paste or oils.

It is desirable that the pretreating solution does not contain an excessof metal ions such as a sodium ion, and further be acidic, neutral, orweakly alkaline such as having a pH not exceeding 8. This is because,when these requirements are satisfied, the color developer converts theterminal group of the fiber from --SO₃ ⁻ Na⁺ to --SO₃ ⁻ NH₄ ⁺, i.e.,causes ion exchange between Na⁺ and NH₄ ⁺, to promote the colordevelopment, and also because the color developer, being a salt or anacid, may sometimes be ineffective in the alkali range where the pH is 8or higher.

The heat treatment of a fiber product dyeable with cationic dyes with apretreating solution comprises heating a bath containing, for example, asolution of the above described composition, immersing the fiber producttherein, and then washing the same with water followed by drying.

The heating may be advantageously conducted at a temperature not lowerthan the apparent transition point of the fiber, for example, about 80°to 90° C. in the case of acrylic fibers, and preferably 80° to 100° C.in most cases, for a period of about 5 to 60 min. After the heattreatment, it is desirable that the fiber product be cooled gradually sothat the material to be transfer-printed will undergo no deformation.

As described hereinabove, by causing a coloring agent comprising acarbinol base of a basic dye or its derivative to coexist with a strongbase in an ink or by further using a specific solvent system, thepresent invention has succeeded in the preparation of an ink for heattransfer printing and a transfer sheet obtained by using the same, bothhaving remarkably improved storage stability while retaining the heattransferability of the coloring agent, whereby the commodity value ofthe ink and the transfer sheet is crucially enhanced.

In order to indicate more fully the nature and utility of thisinvention, the following specific examples of practice constitutingpreferred embodiments of the invention are set forth, it beingunderstood that these examples are presented as illustrative only andnot intended to limit the scope of the invention. Throughout theseexamples, quantities expressed in "parts" are "parts by weight".

EXAMPLE 1

100 parts of polyvinyl butyral (trade name: Eslec BL-1, manufactured bySekisui Kagaku K. K.), 50 parts of the carbinol base of Aizen CathilonPink FGH (C.I. Basic Red 13(48015), a basic dye manufactured by HodogayaKagaku K. K.), 95 parts of sodium carbonate, and 5 parts of TeepolB18(an anionic surfactant manufactured by Daiichi Kogyo Seiyaku K. K.)were thoroughly kneaded with 750 parts of a xylene/isopropyl alcohol(1:1) solvent mixture to prepare a red ink composition.

This ink composition was applied on a gravure paper by the gravureprocess to form a desired pattern, whereby a transfer sheet wasobtained.

The transfer sheet thus obtained was superposed on plain weave cloth ofa polyacrylonitrile fiber of 0.4-mm thickness, and both were heated withan iron heated to 180° C. for 30 seconds. By peeling off the sheet fromthe cloth, transfer-printed cloth which was clearly printed with redcolor was obtained.

The ink composition and the transfer sheet obtained above did notsubstantially deteriorate even after storage for 2 months while thoseobtained in the absence of sodium carbonate deteriorated in 48 hours.

Similar results were obtained with a blue ink composition prepared byreplacing the carbinol base of Aizen Cathilon Pink FGH described aboveby the carbinol base of Astrazon Blue FRR (C.I. Basic Blue 69manufactured by Beyer A. G.).

Further, polyester cloths dyeable with cationic dyes were similarlytransfer-printed by using the above transfer sheets, whereupontransfer-printed cloths printed respectively with red and blue colorswere obtained. These results clearly show that these ink compositionscan be used for polyester cloth dyeable with cationic dyes.

EXAMPLE 2

10 parts of Diacryl Golden Yellow GL-N (C.I. Basic Yellow 28) and 2parts of sodium methylate were caused to react with each other in 88parts of thoroughly dehydrated methanol, and then the methyl derivativeof the carbinol base of the dye (coloring agent) was obtained in theusual way.

Subsequently, 5 parts of the coloring agent thus obtained, 10 parts ofethyl cellulose (N-7CP, Hercules Company), and 2 parts of sodiumhydroxide were thoroughly kneaded with 80 parts of a xylene/butanol(1:1) solvent mixture to prepare a yellow ink composition.

By using this ink composition, a transfer sheet was produced, andtransfer-printed cloth of yellow color was obtained by the transferprocess in the same manner as in Example 1.

The ink composition and the transfer sheet showed the same storagestability as those obtained in Example 1.

On the other hand, an ink composition prepared in the same manner exceptthat no sodium hydroxide was added and a transfer sheet obtained byusing the same had good transferability, but resulted in discolorationafter storage for about 48 hours.

EXAMPLE 3

An ink comprising 10 parts of ethyl cellulose, 4 parts of the carbinolbase of Aizen Cathilon Yellow 3GLH (C.I. Basic Yellow 11 (48055)), 2parts of sodium hydroxide, and 84 parts of a xylene/butanol (1:1)solvent mixture was applied on a gravure paper by the gravure process toform a desired pattern, whereby a transfer sheet was obtained.

By using the transfer sheet thus obtained, cloth of an acrylic fiber(Casimilon manufactured by Asahi Kasei K. K.) was transfer-printed at atemperature of 200° C. and under a pressure of 1 kg/cm² for 30 seconds,whereupon clearly printed cloth was obtained.

There was no difference between the transfer-printed cloth obtained witha transfer sheet stored for 2 months after preparation and thatsimilarly obtained with a freshly prepared transfer sheet.

On the other hand, a transfer sheet obtained by using an ink prepared inthe same manner as is described above except that no sodium hydroxidewas added resulted in reduction in concentration in a pale-coloredportion after storage for about 48 hours.

EXAMPLE 4

An ink comprising 8 parts of ethylhydroxyethyl cellulose, 5 parts of thecarbinol base of Aizen Cathilon Pink FGH (C.I. Basic Red 13), 5 parts ofpotassium carbonate and 82 parts of a xylene/butanol (7:3) solventmixture was applied on a glassine paper by the gravure process to form adesired pattern, whereby a transfer sheet was obtained.

Subsequently, cloth of an acrylic fiber (Vonnel, Mitsubishi Rayon K. K.)was immersed in a bath containing 30 g of ammonium tartrate, 3 g of annonionic surfactant (Noigen HC, Daiichi Kogyo Seiyaku K. K.) and 3 g ofsodium tripolyphosphate, respectively, for 1 l of water, the weightratio of the cloth to the bath (bath ratio) being 1:30, at 90° C. for 15minutes. After the cloth thus treated was washed with water and dried,heat transfer was carried out with the above described transfer sheet at200° C. for 30 seconds under a pressure of 1.0 kg/cm², whereupon clearlyand uniformly transfer-printed cloth of satisfactory color fastness wasobtained.

A comparative sample prepared from cloth treated with only ammoniumtartrate and transfer-printed under the same conditions was found to beunevenly printed in part.

EXAMPLE 5

Cloth of a polyester fiber dyeable with cationic dyes (Toraylon, plainweave fabric, Toray K. K.) was immersed in a bath containing 40 g ofurea and 3 g of a nonionic surfactant (Solge MH-7, Meisei Kagaku K. K.),respectively, for 1 l of water, the bath ratio being 1:30, at 90° C. for15 minutes. After the cloth thus treated was washed with water anddried, heat transfer was carried out with the same transfer sheet as inExample 1 at 200° C. for 30 seconds under a pressure of 1.0 kg/cm²,whereupon clearly and uniformly transfer-printed cloth of satisfactorycolor fastness was obtained.

A comparative sample prepared from cloth treated with only urea andtransfer-printed under the same conditions was found to be unevenlyprinted in part.

EXAMPLE 6

100 parts of ethyl cellulose (Ethyl Cellulose N-7CP, Hercules Company),30 parts of the carbinol base of Diacryl Pink (C.I. Basic Red 35, a redbasic dye, Mitsubishi Kasei Kogyo K. K.), and 50 parts of sodiumhydroxide were thoroughly kneaded with 820 parts of a toluene/butanol(1:1) solvent mixture to prepare a red ink composition.

This ink composition was then applied on a gravure paper by the gravureprocess to form a desired pattern, whereby a transfer sheet wasobtained.

The transfer sheet thus obtained was superposed on plain weave cloth ofpolyacrylonitrile fiber of 0.4-mm thickness, and both were heated withiron heated to 180° C. for 30 seconds. By peeling off this sheet,transfer-printed cloth clearly colored in dark red was obtained.

The same transfer printed was carrid out with a transfer sheet obtainedin the same manner by using the above described ink composition whichhad been stored for 2 months at room temperature. The transferredpattern on the transfer-printed cloth thus obtained was found to haveundergone substantially no reduction in concentration as compared withthat obtained by using a freshly prepared ink composition.

Similar results were obtained when transfer printing was carried outwith a transfer sheet obtained by using the above ink composition afterthe sheet was stored for 2 months at room temperature.

SOLVENT TEST

The influence of solvents on the storage stability of inks was evaluatedby replacing 820 parts of the toluene/butanol (1:1) solvent mixture usedin Example 6 by the same quantity of each solvent mixture shown in Table1 below.

The results obtained are listed in the same Table.

                                      TABLE 1(A)                                  __________________________________________________________________________                       Weight Ratio Between Solvents                                                 Run No.                                                    Solvent            1 2 3 4 5 6 7 8 9 10                                                                              11                                                                              12                                                                              13                                                                              14                                                                              15                                                                              16                                                                              17                                                                              18                                                                              19                                                                              20                                                                              21                                                                              22               __________________________________________________________________________    Monohydride                                                                              Isopropyl 2               3               1                        alcohol    alcohol                                                                       Butanol 2     2             3     2 3   1       2                                                                             3                                                                             10                                                                              5                           Methyl                        3       3         3                             cellosolve                                                                    Ethyl           2   2           3       2         5                           cellosolve                                                         Secondary solvent                                                                        Butyl acetate                                                                         4           4                                              component  Toluene 4 4 4 4 4 4   7 7 7 7 7 7 4   3         3                             Xylene                              7 4 7       4                             Methyl iso-                       4                                           butyl ketone                                                                  Isopropyl                                       3                                                                             7                                                                             4                             acetate                                                            __________________________________________________________________________

                                      TABLE 1(B)                                  __________________________________________________________________________               Weight Ratio Between Solvents                                                 Run No.                                                            Solvent    1 2  3  4  5  6  7  8  9  10                                                                              11                                                                              12                                                                              13                                                                              14                                                                              15                                                                              16                                                                              17                                                                              18                                                                              19                                                                              20                                                                              21                                                                              22               __________________________________________________________________________    Other                                                                              Methanol   2        2     3                                              Solvent                                                                            Ethanol                      3                                           Com- Ethyl   4  4                                                             ponents                                                                            acetate                                                                       Methyl        4  4  4  4                                                      ethyl                                                                         ketone                                                                   Storage Stability*                                                            Immediately after                                                             preparation of ink                                                                       O O  O  O  O  Δ                                                                          O  O  O  O O O O O O O O O       O                                                                             O                                                                             O                                                                             O                After 3-day storage                                                                      O X  X  X  X  X  X  X  X  O O O O O O O O O       O                                                                             O                                                                             O                                                                             O                After 30-day storage                                                                     O X  X  X  X  X  X  X  X  Δ                                                                         O Δ                                                                         O Δ                                                                         O Δ                                                                         O Δ Δ                                                                       Δ                                                                       O                                                                             O                After 60-day storage                                                                     Δ                                                                         X  X  X  X  X  X  X  X  X O X O X O X O X       X                                                                             X                                                                             O                                                                             O                Classification**                                                                         In                                                                              Out                                                                              Out                                                                              Out                                                                              Out                                                                              Out                                                                              Out                                                                              Out                                                                              Out                                                                              In                                                                              In                                                                              In                                                                              In                                                                              In                                                                              In                                                                              In                                                                              In                                                                              In      In                                                                            In                                                                            In                                                                            In               __________________________________________________________________________     Footnotes:                                                                    *O: 5th or 4th-5th grade on the Grey scale for discoloration                  Δ: 4th or 3rd-4th grade on the Grey scale for discoloration             X: 3rd or lower grade on the Grey scale for discoloration                     **Classification indicates whether the sample falls within preferred          solvents or not.                                                              In: within preferred solvents                                                 Out: Out of preferred solvents                                           

The procedure for evaluation of the storage stability of each ink wassuch that transfer sheets produced in the same manner as in Example 6 byusing ink compositions prepared in the presence of the above describedsolvents immediately after preparation, and after storage for 3 days, 30days and 60 days at room temperature were used to transfer-print clothsby the same transfer process as in Example 6, and that the appearance ofeach transfer-printed cloth thus obtained was examined with the eyeaccording to the following standard:

Examination Standard

The cloth samples were examined by means of the Grey scale fordiscoloration (JIS L0804) specified in the color fastness test method inaccordance with Japanese Industrial Standard (JIS) and by the samemeasurement method as that for measuring discoloration of dyed fibers.

Further, the samples thus examined were graded ○, Δ and X as set forthin the footnotes to Table 1.

EXAMPLES 7 THROUGH 10 AND COMPARATIVE EXAMPLES 1 THROUGH 11

With ink compositions prepared by replacing the solvent in the inkcomposition of Example 6 by each solvent shown in Table 2 as in thesolvent test described hereinabove or further by excluding sodiumhydroxide therefrom, the influence of these ink components on thestorage stability of each ink was tested as in the aforementionedsolvent test.

In any case where freshly prepared inks were used, satisfactorytransfer-printed cloths were obtained, while in the case where inksafter storage for 3 days, 30 days and 60 days were used, the resultsobtained were as shown in Table 2. It will be noted from the resultsthat these components seriously affect the storage stability of eachink.

                                      TABLE 2                                     __________________________________________________________________________    Composition of Ink                     Storage Stability of Ink                               Sodium                 After                                                                             After                                                                              After                                Basic dye                                                                          Resin                                                                             hydroxide              3   30   60                            Example No.                                                                          (parts)                                                                            (parts)                                                                           (parts)                                                                             Solvent      (parts)                                                                           days                                                                              days days                          __________________________________________________________________________    Example 7                                                                            30   100 50    Toluene/Butanol = 7/3                                                                      820 O   O    O                             Example 8                                                                            "    "   "     Toluene/Isopropyl                                                                          "   O   Δ                                                                            X                                                   alcohol = 7/3                                           Comparative                                                                   Example 1                                                                            "    "   "     Toluene/Ethanol = 7/3                                                                      "   X   X    X                             Comparative                                                                   Example 2                                                                            "    "   "     Toluene/Butanol/                                                                           "   X   X    X                                                   Ethanol = 4/3/3                                         Example 9                                                                            "    "   "     Toluene/Butanol/                                                                           "   O   O    Δ                                             Butyl acetate = 4/3/3                                   Example 10                                                                           "    "   "     Toluene/Butanol/                                                                           "   O   O    O                                                   Ethyl cellosolve = 4/3/3                                Comparative                                                                   Example 3                                                                            "    "   "     Toluene/Butanol/Methyl                                                                     "   X   X    X                                                   ethyl ketone = 4/3/3                                    Comparative                                                                   Example 4                                                                            "    "   0     Toluene/Butanol = 5/5                                                                      "   O   Δ                                                                            X                             Comparative                                                                   Example 5                                                                            "    "   "     Same as Example 7                                                                          "   Δ                                                                           X    X                             Comparative                                                                   Example 6                                                                            "    "   "     Same as Example 8                                                                          "   X   X    X                             Comparative                                                                   Example 7                                                                            "    "   "     Same as Comparative                                                                        "   X   X    X                                                   Example 1                                               Comparative                                                                   Example 8                                                                            "    "   "     Same as Comparative                                                                        "   X   X    X                                                   Example 2                                               Comparative                                                                   Example 9                                                                            "    "   "     Same as Example 9                                                                          "   O   Δ                                                                            X                             Comparative                                                                   Example 10                                                                           "    "   "     Same as Example 10                                                                         "   O   Δ                                                                            X                             Comparative                                                                   Example 11                                                                           "    "   "     Same as Comparative                                                                        "   X   X    X                                                   Example 3                                               __________________________________________________________________________

EXAMPLE 11

An ink composition comprising 10 parts of ethyl cellulose, 5 parts ofthe carbinol base of Aizen Cathilon Yellow 3GL-H, a yellow dye (C.I.Basic Yellow 11 (48055)), 5 parts of sodium hydroxide, and 84 parts of atoluene/butanol (1:1) solvent mixture was prepared.

9 parts of this ink composition was admixed with 1 part of the inkcomposition of Example 6 to prepare an orange ink composition.

This ink composition was then applied on a glassine paper by the gravureprocess to form a desired pattern, whereby a transfer sheet wasobtained.

The above described ink composition and transfer sheet were subjected tothe same 2-month storage test as in Example 6 and found to have similarstorage stability.

EXAMPLES 12 THROUGH 14 AND COMPARATIVE EXAMPLES 12 THROUGH 19

The red dye of Example 6 and the yellow dye of Example 11 were used inthe blend ratios set forth in Table 3 to prepare orange inkcompositions, and the storage stability of each of the ink compositionswas tested in the same manner.

The use of any of the freshly prepared orange ink compositions resultedin good transfer-printability, and the results obtained from the inksafter storage for 3 days, 30 days and 60 days were as shown in Table 3below.

                                      TABLE 3                                     __________________________________________________________________________           Composition of Ink                Storage Stability of Ink                    Yellow   Ethyl                    After                                                                             After                                                                              After                       Example                                                                              dye Red dye                                                                            Cellulose                                                                          NaOH                3   30   60                          No.    (parts)                                                                           (parts)                                                                            (parts)                                                                            (parts)                                                                           Solvent (parts) days                                                                              days days                        __________________________________________________________________________    Example 12                                                                           45  5    100  50  Toluene/Butanol = 7/3                                                                     800 O   O    O                           Example 13                                                                           "   "    "    "   Toluene/Isopropyl                                                                         "   O   Δ                                                                            X                                                    alcohol = 7/3                                        Comparative                                                                   Example 12                                                                           "   "    "    "   Toluene/Ethanol = 7/3                                                                     "   X   X    X                           Comparative                                                                   Example 13                                                                           "   "    "    "   Toluene/Butanol/                                                                          "   X   X    X                                                    Ethanol = 4/3/3                                      Example 14                                                                           "   "    "    "   Toluene/Butanol/                                                                          "   O   O    Δ                                              Butyl acetate = 4/3/3                                Comparative                                                                   Example 14                                                                           "   "    "    0   Same as Example 12                                                                        "   Δ                                                                           X    X                           Comparative                                                                   14     "   "    "    "   Same as Example 13                                                                        "   X   X    X                           Comparative                                                                   Example 16                                                                           "   "    "    "   Same as Comparative                                                                       "   X   X    X                                                    Example 12                                           Comparative                                                                   Example 17                                                                           "   "    "    "   Same as Comparative                                                                       "   X   X    X                                                    Example 13                                           Comparative                                                                   Example 18                                                                           "   "    "    "   Same as Example 14                                                                        "   Δ                                                                           X    X                           Comparative                                                                   Example 19                                                                           "   "    "    "   Toluene/Butanol = 5/5                                                                     "   Δ                                                                           X    X                           __________________________________________________________________________

The deterioration of inks of a mixed color appeared as a change in huefrom orange to yellow. This is considered to be because the red dye,which was used in such a small quantity as 10%, was more liable toundergo a considerable change.

EXAMPLE 15

100 parts of ethyl cellulose (Ethyl Cellulose N-7CP, Hercules Company),50 parts of the carbinol base of Aizen Basic Cyanine 6GH (C.I. BasicBlue 1, a basic dye, Hodogaya Kagaku K.K.), and 50 parts of sodiumhydroxide were thoroughly kneaded with 800 parts of a toluene/butanol(1:1) solvent mixture to prepare a blue ink composition.

1 part of this ink composition was admixed with 9 parts of the yellowink composition of Example 11 to prepare a green ink composition.

The above described ink composition and transfer sheet obtainedtherefrom were subjected to the same 2-month storage test as in Example6 and found to have similar storage stability.

EXAMPLES 16 THROUGH 18 AND COMPARATIVE EXAMPLES 20 THROUGH 27

The storage stability corresponding to that of Example 15 was tested inthese Examples with ink compositions prepared by adding to 45 parts ofthe yellow dye of Example 11, 5 parts of the blue dye of Example 15 and100 parts of ethyl cellulose the solvents and sodium hydroxide in thequantities shown in Table 4.

The use of any of the freshly prepared ink compositions resulted in goodtransfer-printability, and the results obtained from the inks afterstorage for 3 days, 30 days and 60 days were as shown in Table 4 below.

The deterioration of inks appeared as a change in hue from green toyellow.

                                      TABLE 4                                     __________________________________________________________________________           Additional Components       Storage Stability of Ink                          NaOH                        After 3                                                                           After 30                                                                           After 60                          Example No.                                                                          (parts)                                                                           Solvent             (parts)                                                                           days                                                                              days days                              __________________________________________________________________________    Example 16                                                                           50  Toluene/Butanol = 7/3                                                                             800 O   O    O                                 Example 17                                                                           "   Toluene/Isopropyl alcohol = 7/3                                                                   "   O   Δ                                                                            X                                 Comparative                                                                   Example 20                                                                           "   Toluene/Ethanol = 7/3                                                                             "   X   X    X                                 Comparative                                                                   Example 21                                                                           "   Toluene/Butanol/Ethanol = 4/3/3                                                                   "   X   X    X                                 Example 18                                                                           "   Toluene/Butanol/Butyl acetate = 4/3/3                                                             "   O   O    Δ                           Comparative                                                                   Example 22                                                                           0   Same as Example 16  "   Δ                                                                           X    X                                 Comparative                                                                   Example 23                                                                           "   Same as Example 17  "   X   X    X                                 Comparative                                                                   Example 24                                                                           "   Same as Comparative Example 20                                                                    "   X   X    X                                 Comparative                                                                   Example 25                                                                           "   Same as Comparative Example 21                                                                    "   X   X    X                                 Comparative                                                                   Example 26                                                                           "   Same as Example 18  "   Δ                                                                           X    X                                 Comparative                                                                   Example 27                                                                           "   Same as Example 15  "   Δ                                                                           X    X                                 __________________________________________________________________________

EXAMPLES 19 THROUGH 22 AND COMPARATIVE EXAMPLES 28 THROUGH 35

The storage stability was similarly tested with ink compositionsprepared by adding to 9 parts of the yellow dye of Example 11, 45 partsof the blue dye of Example 15 and 100 parts of ethyl cellulose thesolvents and sodium hydroxide in the quantities shown in Table 4.

The use of any of the freshly prepared ink compositions resulted in goodtransfer-printability, and the results obtained from the inks afterstorage for 3 days, 30 days and 60 days were as shown in the followingTable 5:

                                      TABLE 5                                     __________________________________________________________________________           Additional Component        Storage Stability of Ink                   Example                                                                              NaOH                        After 3                                                                           After 30                                                                           After 60                          No.    (parts)                                                                           Solvent             (parts)                                                                           days                                                                              days days                              __________________________________________________________________________    Example 19                                                                           50  Toluene/Butanol = 5/5                                                                             796 O   O    O                                 Example 20                                                                           "   Toluene/Butanol = 7/3                                                                             "   O   O    O                                 Example 21                                                                           "   Toluene/Isopropanol = 7/3                                                                         "   O   Δ                                                                            X                                 Comparative                                                                   Example 28                                                                           "   Toluene/Ethanol = 7/3                                                                             "   X   X    X                                 Comparative                                                                   Example 29                                                                           "   Toluene/Butanol/Ethanol = 4/3/3                                                                   "   X   X    X                                 Example 22                                                                           "   Toluene/Butanol/Butyl acetate = 4/3/3                                                             "   O   O    Δ                           Comparative                                                                   Example 30                                                                           O   Same as Example 19  "   Δ                                                                           X    X                                 Comparative                                                                   Example 31                                                                           "   Same as Example 20  "   Δ                                                                           X    X                                 Comparative                                                                   Example 32                                                                           "   Same as Example 21  "   X   X    X                                 Comparative                                                                   Example 33                                                                           "   Same as Comparative Example 28                                                                    "   X   X    X                                 Comparative                                                                   Example 34                                                                           "   Same as Comparative Example 29                                                                    "   X   X    X                                 Comparative                                                                   Example 35                                                                           "   Same as Example 22  "Δ                                                                          X   X                                      __________________________________________________________________________

The deterioration of inks appeared as a change in hue from dark green toblue.

EXAMPLE 23

100 parts of ethyl cellulose (Ethyl Cellulose N-7CP, Hercules Company),60 parts of a dye powder of Diacryl Pink R-N (C.I. Basic Red 35, a basicdye, Mitsubishi Kasei Kogyo K.K.) having a concentration of 200%, and 50parts of sodium hydroxide were thoroughly kneaded with 820 parts of atoluene/butanol (1:1) solvent mixture. The resulting mixture was thenleft standing for 2 days and the precipitate formed was removed, wherebya red ink composition was obtained.

The ink composition thus obtained was found to have the same storagestability as that of the ink composition of Example 6.

EXAMPLE 24

Ink compositions prepared by replacing the binder Ethyl Cellulose N-7CPand the alkali agent NaOH used in the ink compositions of Examples 6through 23 and Comparative Examples 1 through 35 by ethyl hydroxyethylcellulose and KOH, respectively, were found to have exactly the samestorage stability.

EXAMPLE 25

The inks prepared in Examples 6 through 22 and Comparative Examples 1through 35 were immediately applied on glassine papers by the gravureprocess to form desired patterns, whereby transfer sheets were obtained.

When the transfer sheets immediately after preparation were used totransfer-print cloths of an acrylic fiber (Casimilon, Asahi Kasei K.K.)under the conditions of 200° C. and 1 kg/cm² for 30 seconds, all thetransfer-printed cloths obtained had good color development.

On the other hand, when a transfer sheet printed with a comparative inkwherein no sodium hydroxide was added was used for heat transfer 48hours after ink-printing, the transfer-printed cloth obtained wasreduced in concentration.

In contrast, in the case of a transfer sheet printed with an inkcontaining sodium hydroxide, there was no difference between thetransfer-printed cloth obtained with a sheet 2 months after ink-printingand that obtained with a sheet immediately after ink-printing.

EXAMPLE 26

The ink composition of Example 23 was applied on a glassine paper by thegravure process to form a desired pattern, whereby a transfer sheet (1)was obtained.

Separately, the ink prepared as in Example 23 except that the kneadedink components were not left standing for 2 days was applied on aglassine paper by the gravure process to form a desired pattern, wherebya transfer sheet (2) was obtained.

When the transfer sheets (1) and (2) were used to transfer-print clothsof an acrylic fiber (Casimilon, Asahi Kasei K.K.) under the conditionsof 200° C. and 1 kg/cm² for 30 seconds, the transfer sheet (1) resultedin good color development while the transfer sheet (2) resulted insomewhat lower concentration.

When the transfer sheets (1) and (2) were stored for 2 months under thesame conditions and thereafter used for the same transfer process asabove, the transfer sheet (1) gave no change in transferred colorconcentration while the transfer sheet (2) gave reduction in transferredconcentration.

We claim:
 1. A transfer sheet comprising a substrate sheet and acoloring layer provided thereon, the coloring layer containingfrom about1 to about 80 weight percent of a coloring agent comprising at least oneof carbinol bases of basic dyes and their derivatives, wherein each ofsaid derivatives is the product of the reaction between a correspondingbasic dye and an alcoholate, and said coloring agent is sublimable at atemperature between about 80° C. and about 250° C.; from about 1 toabout 80 weight percent of a strong base, wherein the mole ratio of saidstrong base to said coloring agent is between about 1:1 to about 40:1;and the remainder a binder, wherein all weight percents are based on thetotal weight of said coloring layer.
 2. A transfer sheet as claimed inclaim 1 in which the coated weight of the coloring layer on a dry basisis 0.2 to 4 g/m².
 3. A transfer sheet as claimed in claim 1 in which thecarbinol base derivatives are represented by the formula:

    Dy--O--R

wherein Dy is a cationic moiety of a basic dye, and R is an alkyl grouphaving 1 to 4 carbon atoms, a benzyl group or a phenyl group.
 4. Atransfer sheet as claimed in claim 1 in which the strong base isselected from the group consisting of hydroxides and alcoholates ofalkali metals and alkaline earth metals.
 5. A transfer sheet as claimedin claim 1 in which the strong base is sodium hydroxide or potassiumhydroxide.
 6. A transfer sheet as claimed in claim 1 in which the binderis selected from ethyl cellulose, ethylhydroxyethyl cellulose,hydroxypropyl cellulose, hydroxypropyl methyl cellulose, polyvinylalcohol, polyvinyl formal, polyvinyl butyral, polyvinyl acetate, andpolyvinyl pyrrolidone.
 7. A transfer sheet as claimed in claim 1 inwhich the coloring layer has been obtained by applying on the substratesheet an ink composition comprising 0.1 to 10% by weight of saidcoloring agent, 0.1 to 10% by weight of said strong base in theproportion of 1 to 40 moles per mole of the coloring agent, 5 to 20% byweight of said binder, and the remainder being a solvent containing 80%or more of a monohydric alcohol having a total of 3 to 6 carbon atoms,wherein all weight percents are based on the total weight of said inkcomposition.
 8. A transfer sheet as claimed in claim 1 in which thecoloring layer has been obtained by applying on the substrate sheet anink composition comprising 0.1 to 10% by weight of said coloring agent,0.1 to 10% by weight of said strong base in the proportion of 1 to 40moles per mole of the coloring agent, 5 to 20% by weight of said binder,and the remainder being a solvent containing a total of 80% or more of amonohydric alcohol having a total of 3 to 6 carbon atoms and a secondarysolvent component selected from the group consisting of butyl acetate,isopropyl acetate, toluene, xylene and methyl isobutyl ketone.
 9. Atransfer sheet as claimed in claim 8 in which the ratio of themonohydric alcohol to the secondary solvent component used in the inkcomposition is 2/8 to 4/6 on a weight basis.
 10. A transfer sheet asclaimed in claim 1 in which the coloring layer further comprises aconventional quantity of a conventional additive selected from the groupconsisting of plasticizers, stabilizers, waxes, greases, drying agents,hardening agents, emulsifiers, dispersants, fillers, and non-sublimablepigments and dyes.
 11. A transfer sheet as claimed in claim 1 in whichthe coloring layer has thereon an overcoat layer of a thickness of 0.5to 10 um comprising a film forming resin.
 12. A heat transfer printingprocess which comprises:superposing a transfer sheet comprisingasubstrate sheet and a coloring layer of a desired pattern provided onthe substrate sheet, the coloring layer containing from about 1 to about80 weight percent of a coloring agent comprising at least one ofcarbinol bases of basic dyes and their derivatives, wherein each of saidderivatives is the product of the reaction between a corresponding basicdye and an alcoholate, and said coloring agent is sublimable at atemperature between about 80° C. and about 250° C.; from about 1 toabout 80 weight percent of a strong base, wherein the mole ratio of saidstrong base to said coloring agent is between about 1:1 to about 40:1;and the remainder a binder, wherein all weight percents are based on thetotal weight of said coloring layer,on a transfer receiving basematerial consisting of a fiber dyeable with cationic dyes in such amanner that the surface of the transfer sheet provided with the coloringlayer contacts the base material to form a superposed structure; andmaintaining the superposed structure under heat, at a temperaturesufficient to sublime said coloring agent, and pressure.
 13. A heattransfer printing process as claimed in claim 12 in which the heatingand pressing treatment is carried out at a temperature of 80° to 250° C.and a pressure of 20 g to 20 kg/cm² for 10 to 180 seconds.
 14. A heattransfer printing process as claimed in claim 12 or 13, which processfurther comprises pretreating the transfer receiving base material byimmersing the same in an aqueous solution comprising water; 5 to 100 gper liter of water of a color developer having a radical selected fromthe group consisting of an ammonium group, an amino group and an acidamide group, organic acids, and inorganic acids; and 0.5 to 3 g perliter of water of a homogenizing agent selected from nonionic andanionic surfactants.
 15. A heat transfer printing process as claimed inclaim 14 in which the aqueous solution has a pH not exceeding
 8. 16. Aheat transfer printing process as claimed in claim 14 in which thepretreatment is carried out at a temperature of 80° to 100° C. for 5 to60 minutes.